When GNOME did its version 3 and Ubuntu came up with Unity, the popularity of Linux Mint sky-rocketed, because they stuck with GNOME 2.32. The Mint team has been working on their next version for a while now, and today, they first unveiled what they're working on. There's good news - the team is working on making GNOME 3 likeable. Their question for this release: "How do we make people like Gnome 3? And what do we provide as an alternative to those who still do not want to change?"

I believe Mate will still be preferable to MGSE. Since Gnome Shell is slower than Gnome 2. Also right now, MGSE doesn't look anywhere close to as polished as Mint 11. It sounds like it will take quite a few releases before it is.